def add_two_numbers(a, b):
    return a + b

print(add_two_numbers(10, 20))


def is_prime(n):
    if n <= 1:
        return False
    for i in range(2, int(n**0.5)+1):
        if n % i == 0:
            return False
    return True

print(is_prime(23))

#递归实现阶乘
def factorial(n):
    if n == 0:
        return 1
    else:
        return n * factorial(n-1)
print(factorial(5))